Emergency signal devices are employed in various forms in a number of different situations. By sheer numbers of vehicles that are disabled on the highways for varying lengths of time, there is the obvious highway application for emergency signal devices.
Backpackers and campers also need some type of emergency signal device. Especially in the western and southwestern United States, backpackers may become lost in deserts, in mountainous woods, in the snow or in other situations in which search crews may not find them in time to save their lives. This is particularly a problem with children who wander away from campsites or from trails and possibly perish in the wilderness.
In addition to the traffic safety and camper uses, emergency signals are also needed for downed aircraft and disabled boats. Mountain climbers and desert motorcyclists and others who could find themselves in a dangerous position would find a compact and lightweight emergency signal device to be vital.
Some situations may call for a radio transmitter for help in isolating the victims by an aerial search crew with radio search techniques. Other situations call for a visual means of finding the victims, or a visual means of notifying others that there is a problem, such as along the highway.
Yet another and rarely addressed emergency situation involves invalids and older people. If suddenly stricken with a debilitating problem, a low-cost remote controlled sign that would flash a message such as "Help", or simply light control panels, in a window, could save the lives of older or disabled people who are so stricken that are unable to get to the telephone. Such a device could also include other attention getting means such as an audible signal.
There is a need therefore for a compact, versatile emergency signal that lends itself to a wide variety of applications and is relatively economical to manufacture and produce.
Power supplies have been proposed for electronic flash purposes where the circuit, operating from a power source, functions with means for charging and discharging a capacitor for operating a flash lamp. Typically, many of the systems have had means of some type for sensing the capacitor voltage and disabling the charging circuit after the capacitor has been fully charged, to save power.
The prior art systems mentioned above generally have limitations which make them not suitable for use for emergency signal devices which require an immediate bright flash in response to actuation, rapid recharging to afford repetitive or sequential flashing, or both, and relative light weight. These prior systems typically have a relatively long charging time, between 6 and 30 seconds, or have relatively large sources of power, such as large or bulky batteries, or are connected to an AC source and are thereby non-portable. Also these systems, in order to achieve the desired results, are frequently quite complex as well as being too large to be easily portable in vehicles, such as automobiles, trucks, boats, airplanes, cycles or for backpacking and hiking. Another problem with many prior art systems is that the voltage sensing mechanism is not precise so there is a relatively large swing between full charge of the flash capacitor and the voltage level at which the charge again builds up. They often use a linear technology or a flyback transformer in the feedback circuit.